8. there are 10 balls in a bag numbered from 1 to 10. three balls are selected at random without replacement.
a. how many different ways are there of selecting the three balls?
b. what is the probability that one of the balls selected is the number 5?

a. 720

b. 0.3

Step-by-step explanation:

a.

Three balls are selected at random without replacement.

First ball can be selected in 10 ways

Second ball can be selected in 9 ways

Third ball can be selected in 8 ways

Thus, there are 10×9×8 =720 different ways of selecting three balls.

b.

There are three cases that satisfy this condition

Each probabilities are:

Thus, one of the balls selected is the number 5 is then

94

step-by-step explanation:

average the numbers and use a variable to figure out the minimum to get a 90.

(79+94+91+92+x)/5=90

x = 94